The present invention broadly relates to the spinning of yarn or the like according to the open end-friction spinning principle.
Generally speaking, the method of the present invention is for spinning a yarn or the like in accordance with the open end-friction spinning principle and comprises the steps of separating fibers from a body of fibers, transporting the fibers in a freely floating state by means of a pneumatic fiber transporting airstream guided in a fiber transport passage or channel in a direction of movement inclined at a predetermined acute angle to the opening of the transport passage, subsequently transferring the fibers to a moving perforated surface of a friction spinning means or element which is subjected to underpressure or vacuum, the friction spinning means or element being arranged to intercept the pneumatic fiber transporting airstream, the moving perforated surface being arranged to permit the pneumatic fiber transporting airstream to pass through the moving perforated surface, employing the friction spinning means for forming the fibers into a yarn at a yarn formation position or location, and withdrawing the formed yarn in a predetermined withdrawal direction.
The apparatus of the present invention is for performing a method for spinning a yarn and comprises means for separating fibers from a body of fibers, a friction spinning means or element having a perforated surface defining a yarn formation position or location, a fiber transport passage or channel having an exit opening situated substantially parallel to and at a predetermined spacing from the yarn formation position or location, the fiber transport passage or channel being arranged to forward the fibers pneumatically to the perforated surface for forming the fibers into a yarn, and a yarn withdrawing means for withdrawing the formed yarn.
From previous publications regarding the open end-friction spinning method, it is known to open a fiber sliver to form individual fibers by means of an opening roller known from the open end-rotor spinning method. These fibers are combed from the sliver by needles or teeth of the opening roller, which rotates at high speed. The fibers are transferred to a transporting airstream for transport to a friction spinning means or element.
The fibers in the transporting airstream are in a disordered or random state and are not stretched-out or extended. Delivering the fibers to the friction spinning means in this state, presents poor initial conditions for spinning a yarn of usable quality.
One proposal for delivering fibers in a drawn-out or extended state or condition is advanced in German Patent Publication, No. 3,324,001, published Jan. 3, 1985. In that proposal, obstacles, for example in the form of needles inclined in the fiber transport direction, are provided in the transport passage; the fibers are temporarily caught or at least braked by these obstacles. The fibers are then drawn out or extended by the airstream so as to be delivered in this drawn-out or extended state for subsequent formation of a yarn.
The disadvantage of such obstacles lies primarily in the risk that relatively large fiber clumps or conglomerations at least temporarily will form on the obstacles.
Such fiber clumps may then dislodge and be transported onwards as a unit and may then be supplied to the forming yarn end, resulting in unacceptable neps in the yarn. Another risk lies in the possibility of at least partial blockage of the transport passage or channel.
Another proposal for delivering fibers in a drawn-out or extended state, and in as parallel as possible a state or condition, into the convergent space between two friction spinning drums is set forth in German Patent Publication, No. 3,318,924, published Nov. 29, 1984. In that proposal, a slot-shaped fiber feed passage has a bulge in the region of its exit opening in the wall lying opposite the convergent space; this bulge is intended to provide the possibility for fibers delivered in a drawn-out or extended form or state to be caught at their front or leading ends by the yarn end in the convergent gap and withdrawn in the opposite direction and then to be laid parallel upon the forming yarn end in a whip-like manner with a so-called centrifugal-drawing or acceleration extension movement, so that thereafter they may be twisted into a yarn. In this arrangement, the fiber transport passage lies substantially in a plane extending through the converging gap and at right angles to the axes of the friction spinning drums or rollers. Furthermore, the fiber transport passage is inclined at an acute angle and opposite to the withdrawal direction of the yarn, for example at an angle of approximately 30.degree. .
The disadvantage of this apparatus is that, after the front ends of the drawn-out or extended fibers have been caught by the yarn end, these fibers are diverted at the withdrawal speed of the yarn, which is relatively low compared with the fiber transport speed in the fiber transport passage, so that the trailing portion of a fiber is diverted only partially in a whip-like fashion, while the remaining portion of this fiber is subjected to longitudinal compression in the convergent gap.
Additional technology in this regard is illustrated and described in the U.S. Pat. application Ser. No. 06/773,998, filed Sept. 9, 1985, and entitled "METHOD AND APPARATUS FOR THE PRODUCTION OF A YARN", in which the fibers are delivered neither parallel nor at right angles to the yarn end but in a condition intermediate these two dispositions, so that thereafter they are twisted into the yarn end at the yarn formation position or location and are withdrawn as a yarn.
The disadvantage is, however, that in the aforementioned device of this copending United States application the irregularity with which the fibers adopt the abovementioned desired disposition is too great.